This leaves people that need insurance through the ACA in Pinal
County with limited options. Currently, Blue Cross Blue Shield of
Arizona is participating in the county, but it has plans to pull
out in 2017.

"Plan A is to try and work with the Blue Cross Blue Shield in
that state or another provider in the state to get them to move
in," Cox said. "The question is if there is any plan B."

The plan B could simply be that there is no exchange offering and
people have to buy insurance on their own, but that presents
issues as well.

"If that's the case, it's mostly going to be unaffordable for
those who are already receiving subsidies," Cox told Business
Insider. "They're no longer going to be eligible for the
subsidies, and it is likely that private coverage is not going to
be affordable without the subsidies."

Cox said that these people would not be subject to any penalties
under the individual mandate, but if they were injured or got
sick during the year, they "could be faced with significant
medical bills."

Even if BCBS stays in Pinal County, the situation will be far
from ideal.

The number of insurers available and competing in a market is
linked closely to the cost of premiums, and the withdrawals
are leaving more and more areas with only one or two insurers.
With that sort of monopoly or duopoly, premiums can increase even
more than they already are.

Cox told Business Insider that the situation in Pinal County will
likely raise calls for a public option, or a government-run
health insurance option similar to Medicare or Medicaid. This
would provide an insurer of last resort for a county like Pinal
and would drive competition where there are limited private
options.

As it stands now, however, there is no such option for Pinal
County and it appears that unless someone steps in, there will be
an Obamacare marketplace, but no one selling anything in it.